Host factors responsible for susceptibility to rheumatic fever will be studied. The biochemical characteristics and tissue distribution of a valvular glycopeptide that possesses antigenic similarity with the streptococal group A carbohydrate will be defined. The basis for the hyper-responsiveness of patients with rheumatic valvular heart disease approached by studying the pattern of antibody response of laboratory animals immunized by various routes with the group A streptococcus. In the streptococcal polysaccharide of beta-N-acetyl glucosaminidase derived of rheumatic and non-rheumatic patients will be examined. Finally, the role of cell-immunity in rheumatic myocarditis as gauged by the cytotoxicity of lymphocytes to myocardial cells in tissue culture, will be further explored. BIBLIOGRAPHIC REFERENCES: Baig, M.M.; and Ayoub, E.M.: Purification and Characterization of Salt Extractable Glycoproteins from Porcine Mitral Valve, Biochemistry 15(12;2585), 1976. Badri, M.S., Zawaneh, S.; Cruz, A.C.; Baer, H.; Spellacy, W.N.; and Ayoub, E.M.: Rectal Colonization with Group B streptococci; Relationship to Vaginal Colonization in Pregnant Women, J. Infect. Dis. 135:308, 1977.